A good horror premise, whether it be for a scary movie or a monster movie, stems from a theme people can relate to. FRANKENSTEINhas to do with arrogance and the misuse of science. With THE EXORCIST, it was the loss of faith. With THE EVIL DEAD and a ton of similar movies, it’s about the primal fear of the woods. With JAWS, it was the primal fear of being eaten alive. With KING KONG, it’s that chicks dig jerks. GODZILLA was all about atomic anxiety. HALLOWEEN is about not feeling safe, even in the suburbs. Just about every zombie film has got something to do with death. Just about every vampire film is about bad sex.

In JENNIFER’S BODY, the theme concerns high school friendships, and the way in which girls in particular can suddenly and cruelly turn on each other. This has happened to every girl I know, and it’s upsetting and weird and usually pointless. Girls can be best of friends one day, and the next there’s a drastic turn for the sadistic, with no explanation. Sometimes they come back; sometimes they stay evil.

I meet more female horror fans as time goes on. They absolutely exist, and I hope that they eventually find this movie. This one’s for them. It’s a clear indication that gutsy horror movies aren’t just made by men – this is a strong, distinctly feminine horror film from director Karyn Kusama, screenwriter Diablo Cody, and stars Megan Fox and Amanda Seyfried. Not that I’m indicating it’s just for ladies – not by a long shot – but I imagine that ladies would especially get a kick out of JENNIFER’S BODY.

Jennifer and Anita (“Needy”) are best friends from childhood who have remained close even if they’ve grown up differently. Needy has a nice-guy boyfriend (Johnny Simmons) but is otherwise insecure and mousy, while Jennifer is Megan Fox in a cheerleader outfit. Jennifer is the alpha-female even before she’s turned into a supernaturally powerful demon in a satanic virgin sacrifice gone horribly wrong. Jennifer starts to need to feast on the insides of high school boys, and ultimately no one but Needy can stop her.

You know a horror movie’s got something going for it when it has a secondary premise that’s clever enough to carry its own movie in an alternate universe. I loved the idea of the nice-guy rock band, headed by an appropriately arch Adam Brody, who turn out to be evil and abduct Jennifer to sacrifice her to the devil in return for fame and fortune. The idea that a Matchbox 20 or a Maroon 5 or some other middle-of-the-road whiteboy band with a number in the title might behind the smiles be satanic and murderous creeps is just hilarious to me. It’s spooky because you’re not sure it’s never happened.

The movie’s not perfect. For one thing, it relies on a heavy bit of suspension of disbelief. Low Shoulder (the band’s name) take a look at Jennifer and Needy and somehow are immediately convinced on the basis of looks alone that the one played by Megan Fox is the virgin. Of course, that’s the conceit that the movie hangs upon – the fact that the band are mistaken is the reason why the demon is summoned. It’s just hard to swallow that they’d make that sort of mistake in the first place.

Also, the movie isn’t particularly scary. While director Kusama sets some amazing mood-establishing shots to begin the scenes, none of the scenes are exactly horrifying. There’s too much humor in Diablo Cody’s dialogue for that, although that’s not at all a bad thing. The most obvious point of comparison to JENNIFER’S BODY, when it comes to tone, is Buffy The Vampire Slayer, which puts it in pretty high company that it maybe doesn’t quite belong in (maybe the movie more than the TV series) – what I’m trying to say, anyway, is that the movie is fun and funny, but it won’t keep anyone from a good night’s sleep.

The cast plays everything right, I think. The relationship between Needy and her boyfriend Chip is sweet and touching, to the point that when he’s put in Jennifer’s sights, you actually are worried for him and are rooting for Needy to save him – a nice inversion of the typical damsel-in-distress nonsense that every other action or horror movie falls back upon. The adults in the movie, though their roles are tiny, are cast well too, from Amy Sedaris as Needy’s mom, to the badass J.K. Simmons playing against type as a sensitive, hilariously curly-haired science teacher.

Front and center, though, is Megan Fox, the instant media supernova whose star has flickered and dimmed some in the past few years. I didn’t come at this movie as a Megan Fox fan, but what I think is unfair is sight-unseen criticism of her acting ability: Before now, all we’ve ever seen her in is TRANSFORMERS. Listen, if all you ever saw of John Turturro was TRANSFORMERS, you’d think John Turturro was a crappy actor too.

Unlike many people in America did, I saw Megan Fox in JENNIFER’S BODY and I’m here to tell you that Megan Fox CAN act. She’s perfectly cast as the girl who every guy wants badly, but who makes the occasional sensitive guy, like Chip, admit to preferring the less flashy girl. Megan Fox is way more believable as a high school girl here than she was in TRANSFORMERS, where she seemed more like a pornstar in a schoolgirl scenario. Here, she plays entitled and pushy and still a little immature. She has chemistry with Amanda Seyfried in the way that you believe their friendship and the way it falls apart. She’s adequately convincing as a man-eating monster, and just as convincing in her weaker, more vulnerable moments, as infrequent as they are. If you skipped JENNIFER’S BODY because you have developed some animosity towards Megan Fox (and I’m not even going to bother to get into the Diablo Cody haters, because none of them wrote anything as good as YOUNG ADULT), that’s not really fair. To yourself!